1. Field of the Invention
The present invention relates to a method for manufacturing a solid-state image sensor.
2. Description of the Related Art
There is known a solid-state image sensor having an arrangement which transfers, by a transfer switch, charges generated by photoelectric conversion in a photoelectric converter to a charge-voltage converter such as a floating diffusion region. Japanese Patent Laid-Open No. 2007-311803 discloses a method for implanting ions into a substrate at an inclined angle with respect to the normal to the surface of the substrate in order to form an impurity region constituting a photodiode. According to this method, ions are also implanted under the gate (transmission gate) of a transfer switch.
If ions are implanted into a substrate at an inclined angle with respect to the normal to the surface of the substrate, a region which is shaded by a mask defining an ion implantation region is produced. If ion implantation into part of a region where the charge accumulation region of a photodiode is to be formed, that is, a region where ions are to be implanted is interfered with, the quantity of charges to be accumulated, that is, the saturated charge quantity, becomes small, thereby narrowing the dynamic range of the solid-state image sensor.